1. Field of the Invention
The invention concerns in general terms lighting and/or signalling devices, such as headlights, intended to be mounted in motor vehicles.
2. Description of the Related Art
More particularly, the invention concerns a lighting and/or signalling device for a vehicle comprising a light source and electronic supply and control means. The invention also concerns a light source capable of being mounted in such a device.
Current technical development in the automotive field is tending towards more integration of components and electronic circuits in vehicles.
In particular, as regards headlights and signalling lights, the proportion of electronics in the composition of products has increased very greatly in the last few years, in particular with the introduction of discharge lamps in headlights and light-emitting diodes in signalling lights.
In the coming years, this development can only continue in lighting and/or signalling systems in view of the progressive introduction of AFS type advanced functions, amongst which there are in particular:                a so-called DBL (Dynamic Bending Light) function: this function makes it possible to direct a light beam produced by a light source, for example by moving a reflector with respect to the light source with which it is associated, so that, when the vehicle reaches a bend, the road is illuminated in an optimum manner;        a so-called FBL (Fixed Bending Light) function: the purpose of this function is to progressively illuminate the verge of the road when the vehicle takes a bend; to this end, an additional light source is provided which progressively supplements the low-beam or high-beam lights during negotiation of a bend;        a so-called DRL (Day Running Light) function: this function provides the continuous lighting of lights of the headlight device, in particular for indicating to pedestrians the presence of the moving vehicle and thus avoiding collisions with pedestrians;        a so-called “Town Light” function. This function provides the broadening of a low-beam type beam whilst slightly reducing its range;        a so-called “Motorway Light” function. This function provides an increase in the range of a low-beam light;        a so-called AWL (Adverse Weather Light) function. This function provides a modification of a low-beam light beam so that the driver is not dazzled by a reflection of his own headlight;        a so-called “Overhead Light” function. This function provides a modification of a low-beam light beam so that gantries situated high up are satisfactorily illuminated by means of the low-beam lights.        
The increasing proportion of electronics in lighting and/or signalling systems is directing current research and development efforts towards a more and more intense integration of electronic circuits and in particular integration on the same substrate of power components and components dedicated to control. Besides the gain in compactness, the integration of electronic components is likely to generate the various known advantageous effects such as better performance and reliability and lower costs.
The integration of power components such as IGBT (Insulated Gate Bipolar Transistors) or MOS transistors poses particular difficulties related to the management of thermal constraints of the circuits.
There is known by the inventive entity an electronic ballast for supplying a xenon discharge lamp comprising on the same substrate four IGBT power transistors and various other analog and digital components.
This ballast according to the prior art is shown in FIG. 2 and is designated 11pa hereinafter.
FIG. 2 shows in a top view the layout of the various chips of the ballast 11pa on a printed circuit type substrate SUBpa. The chips designated P1, P2, P3 and P4 are those of four IGBT power transistors forming a switching bridge of a DC/AC voltage converter which is included in the ballast 11pa. The components globally marked P6 are those of a DC/DC voltage converter and of a control circuit also included in the ballast 11pa.
Known microelectronic techniques are used to lay out the electronic components on the substrate SUBpa and establish the appropriate electrical connections between them.
Although this ballast of the prior art has a level of integration that is already relatively high and satisfies the various constraints, in particular those for high temperature (temperature higher than 150° C.), imposed on this type of circuit in a headlight, it is desirable today to propose new solutions enabling additional advances in the integration of electronic circuits dedicated to lighting and/or signalling systems.